1. Field of the Invention
This invention relates generally to a material handler for loading and unloading open-topped railroad cars. In particular, the material handler of the invention is a self-propelled crane capable of self-loading and self-unloading to and from the top of a railroad car via remote control and is also capable of moving from the top of one railroad car to the top of another railroad car.
2. Background
Railroad cars having an open top are used extensively to transport cargo of various types. Cost effective loading and unloading of open topped railroad cars is problematic. Consequently, various methods and devices have been proposed for efficient loading and unloading operations. For example, U.S. Pat. Nos. 4,723,886 and 4,830,562 to Frederking for “Method and Apparatus for Loading and Unloading Railroad Gondola Cars” teaches a hydraulic excavator having a boom structure and material-handling device mounted on two tracks. The two tracks are movable inwardly or outwardly to fit inside a gondola or on the top edges of the sides of the gondola cars. A ramp is required to allow access into the gondola.
U.S. Pat. No. 6,190,106 to Richardson for “Apparatus for Unloading Open-Top Railroad Cars” teaches a frame for locating on a top of railroad cars onto which an excavator may be set. The frame accommodates an excavator having either wheels or tracked treads and allows an excavator to on load or offload material from atop railroad cars. The frame has arms with attachments provided to slide along the sidewall tops of railroad cars. The boom of the excavator is used to slide the frame along. The patent also teaches a special trailer design that doubles as a ramp for use during loading and unloading.
For safety reasons, it is desirable to distance an operator from heavy equipment during loading and unloading of the equipment onto and off of the tops of railroad cars. Additionally, it is desirable to minimize the weight of such equipment, but still provide a means to anchor the equipment so that it does not topple from the railroad car when the boom is extended and loaded. Further, it is desirable to provide equipment that is capable of self-loading and unloading onto a railroad car without having to provide additional equipment, such as a second crane, ramps, and the like to facilitate loading. It is also desirable to have the capacity of transferring loading and unloading equipment from the top of a first railroad car to the top of a second railroad car of a different size without requiring use of additional equipment.